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yamahaman623
11-22-2008, 06:26 PM
if i were to put a wr 450 dirtbike crank in my yfz to make a true 450 would i have to use a wr piston or could i use a yfz piston
Ride1Rob
11-23-2008, 08:11 PM
WR I think bc of the wrist pen size.
daddio
11-24-2008, 10:16 AM
You are better off putting the '06 or newer YFZ crank in.
People went to the WR swap, before Yamaha came out with the longer stroke '06.
SiC sEnSe
11-26-2008, 12:46 PM
Originally posted by yamahaman623
if i were to put a wr 450 dirtbike crank in my yfz to make a true 450 would i have to use a wr piston or could i use a yfz piston

you can run a WR piston or the yzf450 piston cause the pin size is 18mm u can no longer run a yfz450 piston cause its a 20mm pin
daddio
11-26-2008, 12:54 PM
Originally posted by SiC sEnSe
you can run a WR piston or the yz450f piston cause the pin size is 18mm u can no longer run a yfz450 piston cause its a 20mm pin

Fixed it. ;)
Ride1Rob
11-26-2008, 07:54 PM
I'm with Daddio. Why confuse yourself with will this work or that work when you can just go with the 06 setup. No confusion there!
jshtex
11-26-2008, 08:05 PM
It is my understanding that the WR crank and piston combo is little lighter than the 06 and up yfz and I "think" it is higher compression also.

I could be wrong about all of that you know about the stuff you hear on the net.... :D
Ride1Rob
11-26-2008, 09:40 PM
Same compression ratio. In terms of weight it's not going to make ANY NOTICEABLE difference in performance if it's lighter or not. I had the WR crank and scraped it. Went with the 06 setup.
jshtex
11-27-2008, 06:17 PM
I did some checking and the WR is higher compression.

In the current 09 models they are listed as WR 12.3 to 1 vs 11.4 to 1 for the yfz. And the WR used to be 12.5 to1.

Heck the 06 yfz is even lower compression than the 04 yfz, it had 11.9 to 1.

A lighter rotating assy, will accelerate (Rev) faster. But I don't know that you would "notice" it.
Ride1Rob
11-27-2008, 07:30 PM
Man! That's the first that I've ever heard they have different compression ratios. But from 11.5 to 1 or 11.9 to 1 is not going to make any difference. i was told that even the 13.5 to 1 is only about half a hp more than the stocker.